Abstract : It was found that the waste water of dicyclohexylamine nitrite (DCHN) manufacture is polluted with organic substances chiefly with DCHN and with mineral salts, such as nitrite and sulfate of sodium. It was also found that, when distilling waste waters in the presence of alkali and removing 50% of the distillate, the organic contaminants go completely over into the distillate. The still bottoms from the distillation of waste waters contain only mineral salts, sodium sulfate, and sodium nitrite. The results of the experiments using still residue as fertilizer indicated that it has a favorable effect, by increasing the crop of sugar-beets 124-127% in comparison with the control sample. A method was elaborated for the purification of waste waters. (Author)